1. Field of the Invention
The invention relates to instruments for detecting forces and more specifically to an instrument for detecting-a component of a force with respect to an axis using a body of magnetic material whose position in a cavity changes in response to a force to which the instrument is subjected.
2. Description of the Prior Art
A prior art patent search was conducted prior to preparing this patent application. This search was directed primarily to the location of instruments responsive to changes in a force to which the instrument is subjected with respect to a predetermined axis. Such instruments take many forms, the carpenter's level being an example as applied to the force of gravity.
This search failed to reveal any instruments performing this basic function utilizing magnetic techniques. However, the following prior art patents illustrate various applications of magnetic devices and techniques.
Devices in which a body of magnetic material is suspended in a cavity by a magnetic field are illustrated in U. S. Pat. No. 4,473,259. This patent also illustrates the use of a control system to adjust magnetic fields to maintain the body of magnetic material at the desired location within the cavity. In the specific embodiment the device is used as a bearing with a rotating shaft suspended such that is does not mechanically contact any portion of the structure.
Devices for magnetically suspending bodies of magnetic materials are further illustrated in U.S. Pat. No. 4,273,054. The apparatus illustrated in this patent is primarily intended for use in levitating railroad cars. Magnetically levitated railroad cars are further illustrated in U.S Pat. No. 4,356,772. In addition to illustrating magnetic levitation, this patent illustrates methods and apparatus for damping oscillations in the levitated train.